The U.S. tried to rally support Saturday for a military strike against Syria, running into resistance from the American public and skeptics in Congress, as well as from European allies bent on awaiting a U.N. report about a chemical attack they acknowledge strongly points to the Assad government.

President Barack Obama prepared for a national address Tuesday as a growing number of lawmakers, including fellow Democrats, opposed the use of force.

The American public didn’t yet appear persuaded by Obama’s argument that action is needed to deter the future use of chemical weapons.

Anti-war protesters gathered outside the White House on Saturday to voice their opposition to a U.S. military strike, calling their picket line one that Congress shouldn’t cross as it prepares to vote on the issue.

At least 150 protesters picketed the sidewalk in front of the White House and marched to Capitol Hill, chanting slogans like “They say more war; we say no war” and carrying signs that said a war on Syria would be “Built on a Lie.”

Many lawmakers in both parties oppose Obama’s request for Congress to authorize using military force against Syria for a deadly Aug. 21 chemical gas attack the Obama administration blames on President Bashar Assad. Citing intelligence reports, the administration reported 1,429 people died, including 426 children.

The Senate Foreign Relations Committee cleared the authorization measure earlier this week and the first votes by the full Senate could come Wednesday.

Concerns over military action spawned other protests across the country, including one in New York City’s Times Square and a prayer vigil in Boston that echoed Saturday’s massive gathering at the Vatican.

In New York, anti-Wall Street activists joined the protest along with some Syrian expatriates who said they supported the Assad regime. Some protesters carried signs saying, “No more wars for corporate profit,” and “Cut the Pentagon, not food stamps.”

In Indianapolis, about 150 protesters clustered around the Indiana Statehouse in a church-organized protest opposing military intervention. Other protests were reported in Louisiana and Michigan.

Meanwhile, a U.S. official released a DVD compilation of videos showing victims of the Aug. 21 attack near Damascus.

Secretary of State John Kerry, who met with more than two dozen European foreign ministers Saturday, insisted that international backing to take strong action against Syrian President Bashar Assad’s regime was growing, not receding.

Kerry noted that the ministers, who held an informal meeting of the European Union in Vilnius, Lithuania, made powerful statements condemning the attack, and that increasingly there was a sense of conviction that Assad was to blame. Kerry said the U.S. had agreed to provide additional information to those ministers who were not yet convinced that Assad orchestrated the attack.

The EU endorsed a “clear and strong response” to a chemical weapons attack but didn’t indicate what type of response they were backing. It also said that evidence strongly points to the Syrian government. Still, the EU urged the U.S. to delay possible military action until U.N. inspectors report their findings.

The Europeans were divided on whether military action would be effective. Britain’s Parliament has voted against military action. France had been ready to act last week but held off when Obama declared that he would seek the backing of Congress. French President Francois Hollande’s announcement appeared to catch French Foreign Minister Laurent Fabius off guard.

Earlier Friday, Fabius told EU foreign ministers that there was no need to wait for the U.N. report because it would simply confirm what was already known — that the chemical weapons attack had occurred — but would not say who was responsible.

Hollande indicated Saturday that the U.N. report could be ready in a matter of days, and he would then be prepared to make a decision on a French intervention.

“I said ... that I wanted to wait for the inspectors’ report, which I know will be ready within a very reasonable time period, that is, not that far from the decision of the U.S. Congress,” he told French television after meeting with Lebanese President Michel Suleiman in Nice, France. “So, at that moment, I’ll have all the necessary elements that will let me tell the French people the decision I have made for France.”

However, Martin Nesirky, chief U.N. spokesman, insisted that there would be no preliminary report.

The report on the Aug. 21 attack will be given to the U.N. Security Council and other member states once the lab analysis is complete, Nesirky said.

“We are not saying when that will be, except as soon as feasible,” he told The Associated Press. “This is a scientific timeline, not a political timeline.”

Kerry traveled Saturday from Lithuania to Paris to meet with French official and representatives of the Arab League. He joined French Foreign Minister Laurent Fabius in hailing the EU statement.

“Some don’t believe in taking military action ever at all,” Kerry said. “And some want to wait for one thing or another, but the overwhelming support is moving in the direction of holding the Assad regime accountable.”

Kerry added: “This is growing, not receding in terms of the global sense of outrage of what has happened.”

Fabius said if no action were taken, there would be little hope for a political solution to the crisis.

Obama and other administration officials were preparing a dayslong push to gain public and congressional support for a strike on Syria. The challenges they faced were apparent Saturday. Sen. Mark Pryor, an Arkansas Democrat, said he would oppose military action, and dozens of people picketed outside the White House against Obama’s request.

Pryor said in a statement that the administration had not met his criteria for gaining his support: a compelling national security interest, a clearly defined mission with a definitive end, and a coalition of allies.

“Unless there’s some new information or some new development or circumstance, I just don’t see me changing my vote at this point,” he said.

Saturday’s developments left both the U.S. and Europeans in a waiting game.

While the Europeans awaited the U.N. inspection report, the Obama administration waited to see if Congress would back a use of force. Meantime, administration officials continued to lobby lawmakers by phone to vote to authorize a limited military strike against the Assad regime.

The first Senate vote, expected Wednesday, was likely to be on a resolution authorizing the “limited and specified use” of U.S. armed forces against Syria for no more than 90 days and barring American ground troops from combat. A final vote in the 100-member chamber was expected at week’s end.

A House vote is likely the week of Sept. 16.

Asked about the American public’s uneasiness about getting involved in another conflict, Kerry reiterated his view that the use of chemical weapons in the Syrian conflict was a threat to the U.S.

“This case has not yet been made to the American people for more than a few days and we will continue to make the case to the American people,” Kerry said in Paris. “This concerns ever American’s security.”

The DVD compilation of videos of victims of the gas attack near Damascus was shown to senators during a classified briefing on Thursday, and some of the videos were first broadcast Saturday on CNN. Supporters of the Syrian rebels had posted the videos on YouTube.

Senate Intelligence Committee Chairman Dianne Feinstein of California requested the material from the CIA, and members of her committee watched the videos on Thursday. The DVD is a compilation of footage of victims of the Aug. 21 chemical weapons attack in the suburbs of the Syrian capital of Damasacus that were posted on YouTube by supporters of the Syrian rebels.

The U.S. official, who was granted anonymity to discuss the subject of a classified briefing, said the videos were also referenced in the government’s four-page intelligence assessment, released last week, that blamed the Syrian government for the chemical attack.